Magnetic,dielectric, and transport properties of bismuth pyrostannate Bi2(Sn0.9Mn0.1)2O7

Physics of the Solid State - The effect of replacing manganese ions on the structural, dielectric, transport, and magnetic properties of Bi2(Sn0.9Mn0.1)2O7 has been studied and the correlation...     

Magnetic properties of aerugite Co<Subscript>10</Subscript>Ge<Subscript>3</Subscript>O<Subscript>16</Subscript>

This paper reports on the first study of the temperature and field dependences of the magnetization, heat capacity, and electrical properties of synthesized polycrystalline samples of aerugite Co₁₀Ge₃O₁₆, as well as on x-ray diffraction analysis of this compound. It is shown that the cobalt ions in this compound occupy three nonequivalent positions. The results of the experimental and theoretical studies suggest that aerugite is a ferrimagnet with two uncompensated magnetic moments of the cobalt atom per formula unit.     

Correlation of the magnetic and transport properties with polymorphic transitions in bismuth pyrostannate Bi2(Sn1 − x Cr x )2O7

Physics of the Solid State - The correlation of the electrical, magnetic, and structural properties of Bi2(Sn1 − x Cr x )2O7 solid solutions has been investigated for two compositions with x...     

Electrical Properties of the Polycrystalline BiFe0.95Co0.05O3 Films

Physics of the Solid State - Semiconductor BiFe0.95Co0.05O3 thin-film compounds have been synthesized by a burst technique. The film surface morphology and the effect of electronic doping via...     

Synthesis, crystal structure, and magnetic properties of the Li8FeSm22O38 single crystal

New single crystals of Li₈FeSm₂₂O₃₈ have been grown by spontaneous crystallization from a solution in melt. The structure of these crystals has been determined: it corresponds to the space group Im $\bar 3$ m. Investigations of the magnetic susceptibility in the ranges of temperatures 2?C24 K and fields up to 50 kOe have revealed a magnetic transition near 3 K. The temperature behavior of the magnetic susceptibility of the two-level system has been simulated. The results of the simulation agree with the experimental data. The resonance properties of Li₈FeSm₂₂O₃₈ have been studied in the temperature range 100?C300 K.     

Preparation,structural, and calorimetric characterization of bicomponent metallic photonic crystals

We report preparation and characterization of novel bicomponent metal-based photonic crystals having submicron three-dimensional (3D) periodicity. Fabricated photonic crystals include SiO₂ sphere lattices infiltrated interstitially with metals, carbon inverse lattices filled with metal or metal alloy spheres, Sb inverse lattices, and Sb inverse lattices filled with Bi spheres. Starting from a face centered SiO₂ lattice template, these materials were obtained by sequences of either templating and template extraction or templating, template extraction, and retemplating. Surprising high fidelity was obtained for all templating and template extraction steps. Scanning electron microscopy (SEM), small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to characterize the structure and the effects of the structure on calorimetric properties. To the best of our knowledge, SAXS data on metallic photonic crystals were collected for first time. PACS 42.70.Qs; 68.37.Hk; 61.10.Eq; 81.70.Pg     

Magnetic and electrical properties of bismuth cobaltite Bi24(CoBi)O40 with charge ordering

The compound Bi₂₄(CoBi)O₄₀ has been synthesized using the solid-phase reaction method. The temperature and field dependences of the magnetic moment in the temperature range 4 K < T < 300 K and the temperature dependences of the EPR line width and g-factor at temperatures 80 K < T < 300 K have been investigated. The electrical resistivity and thermoelectric power have been measured in the temperature range 100 K < T < 1000 K. The activation energy has been determined and the crossover of the thermoelectric power from the phonon mechanism to the electron mechanism with variations in the temperature has been observed. The thermal expansion coefficient of the samples has been measured in the temperature range 300 K < T < 1000 K and the qualitative agreement with the temperature behavior of the electrical resistivity has been achieved. The electrical and structural properties of the compound have been explained in the framework of the model of the electronic-structure transition with inclusion of the exchange and Coulomb interactions between electrons and the electron-phonon interaction.     

IR and NMR Spectra of Crystalline and Amorphous Copper Metaborate

IR and NMR spectroscopic investigations of crystalline and amorphous copper metaborate CuB ₂ O ₄ as well as of copper metaborate crystallized from the amorphous state have been carried out for the first time. For an amorphous sample, a new wide absorption band arises in the frequency range ∼1200–1600 cm⁻¹. This band is due to conversion of a number of tetrahedral BO ₄ units of the crystalline sample into the trigonal BO ₃ units. The presence of trigonal units in amorphous CuB ₂ O ₄ is confirmed by the ¹¹B NMR spectra. Based on the data of IR and NMR spectroscopy, significant intensification of the exchange interaction is explained by the formation of shorter exchange bridges during amorphyzation of CuB ₂ O ₄ . __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 73–78, September, 2005.     

Synthesis, crystal structure, and magnetic properties of a Li8FeSm22O38 single crystal

Li₈FeSm₂₂O₃₈ single crystals have been grown by spontaneous flux crystallization, and their structure has been identified by X-ray diffraction analysis as follows: cubic crystals, a = 11.9078(5) Å, sp.gr. $Im\bar 3m$ , Z = 2. Fe atoms occupy two mixed positions. Magnetic ions have different ligand environments: a regular octahedron (Sm/Fe)O₆, a three-cap trigonal prism SmO₉, and a square antiprism SmO₈. The rather low Neel temperature (～3 K) can be explained by the considerable variation in the angles and lengths of exchange couplings between magnetic ions.